disable flaky test (#7086)

Signed-off-by: Sally MacFarlane <macfarla.github@gmail.com>

acceptance-tests/tests/src/test/java/org/hyperledger/besu/tests/acceptance/pubsub/NewPendingTransactionAcceptanceTest.java

@@ -116,6 +116,7 @@ public class NewPendingTransactionAcceptanceTest extends AcceptanceTestBase {
   }
 
   @Test
+  @Disabled("test is flaky - sometimes returns more than 3 total events #6909")
   public void subscriptionToMinerNodeMustReceiveEveryPublishEvent() {
     final Subscription minerSubscription = minerWebSocket.subscribe();